MIMO (multiple-input multiple-output) refers to a method for improving data transmission/reception efficiency by adopting multiple transmit (Tx) antennas and multiple receive (Rx) antennas rather than using a single Tx antenna and a single Rx antenna. A receiving side receives data through a single antenna path when a single antenna is used, whereas the receiving side receives data through multiple paths when multiple antennas are used. Accordingly, MIMO may increase data transfer rate and throughput and improve coverage.
Single-cell MIMO may be classified into single user MIMO (SU-MIMO) in which a single user equipment (UE) receives a downlink signal in a single cell and multi-user MIMO (MU-MIMO) in which two or more UEs receive downlink signals in a single cell.
Meanwhile, a coordinated multipoint (CoMP) system for improving throughput of a UE located at a cell edge by applying improved MIMO to a multi-cell environment is being studied. The CoMP system may reduce inter-cell interference in a multi-cell environment and improve system performance.